A memory device may be implemented with a semiconductor such as silicon (Si), germanium (Ge), gallium arsenide (GaAs), and indium phosphide (InP). The memory device may be classified as a volatile memory device or a nonvolatile memory device.
A nonvolatile memory device is a memory device in which data stored therein does not disappear even when power supply is interrupted. Example nonvolatile memory devices may include a NAND flash memory, a vertical NAND flash memory, a NOR flash memory, resistive random-access memory (RAM) (RRAM), a phase-change memory, magnetoresistive RAM (MRAM), and the like.
A volatile memory device is a memory device in which data stored therein disappears when power supply is interrupted. Example volatile memory devices may include static RAM (SRAM), dynamic RAM (DRAM), a latch, a flip-flop, a register, and the like.
In DRAM, a memory cell array may include bit lines and memory cells connected to a complementary bit line. When a read operation (or a refresh operation) is performed, a bit line sense amplifier may sense and amplify a voltage difference between the bit line and the complementary bit line. The bit line sense amplifier may include a plurality of transistors. As a result of refinement of a manufacturing process, a thickness of a gate-oxide layer of the plurality of transistors has been reduced. However, as the thickness of the gate oxide layer of the plurality of transistors is reduced, a problem occurs in that a gate leakage current is increased in response to an applied voltage.